<template>
  <div class="app-container">
    <h2 style="text-align: center;">发布新课程</h2>
    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="发布课程"/>
    </el-steps>

    <el-form label-width="120px">
        <el-form-item label="课程标题">
            <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
        </el-form-item>
        <!-- 所属分类 TODO -->
        <!-- 课程讲师 TODO -->
        <el-form-item label="课程讲师">
            <el-select
                v-model="courseInfo.teacherId"
                placeholder="请选择">
                <el-option
                    v-for="teacher in teacherList"
                    :key="teacher.id"
                    :label="teacher.name"
                    :value="teacher.id"/>
            </el-select>
        </el-form-item>

        <!-- 一级分类 --><!-- 由于使用了框架可以直接写成oneLevelChange，而不用加后面的(this.value) -->
        <el-form-item label="课程分类">
            <el-select
                v-model="courseInfo.subjectParentId"
                placeholder="一级分类" @change="oneLevelChange">
                <el-option
                    v-for="subject in oneLevelList"
                    :key="subject.id"
                    :label="subject.title"
                    :value="subject.id"/>
            </el-select>
            <el-select
                v-model="courseInfo.subjectId"
                placeholder="二级分类">
                <el-option
                    v-for="subject in twoLevelList"
                    :key="subject.id"
                    :label="subject.title"
                    :value="subject.id"/>
            </el-select>
        </el-form-item>

        <el-form-item label="总课时">
            <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/>
        </el-form-item>
        <!-- 课程简介 TODO -->
        <el-form-item label="课程简介">
            <tinymce :height="300" v-model="courseInfo.description"/>
        </el-form-item>
        <!-- 课程封面 TODO -->

        <!-- 课程封面-->
        <el-form-item label="课程封面">
            <el-upload
                :show-file-list="false"
                :on-success="handleAvatarSuccess"
                :before-upload="beforeAvatarUpload"
                :action="BASE_API+'/edu/oss/file'"
                class="avatar-uploader">
                <img :src="courseInfo.cover">
            </el-upload>
        </el-form-item>

        <el-form-item label="课程价格">
            <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
        </el-form-item>
        <el-form-item>
            <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
        </el-form-item>
    </el-form>
  </div>
</template>
<script>
import subject from "@/api/edu/subject"
import course from "@/api/edu/course"
import Tinymce from '@/components/Tinymce' //引入组件
export default {
  //声明组件
  components: { Tinymce },
  data() {
    return {
      saveBtnDisabled: false, // 保存按钮是否禁用
      courseInfo:{
            title: '',
            subjectParentId:'',//一级分类
            subjectId: '',//二级分类
            teacherId: '',
            lessonNum: 0,
            description: '',
            cover: '/static/01.png',
            price: 0
        },
        teacherList:[],
        oneLevelList:[],
        twoLevelList:[],
        BASE_API: process.env.BASE_API, // 接口API地址
        courseId:''
    }
  },
  created() {
    this.init()    
  },
  watch: {//监听
      $route(to,from){//路由变化方式，路由发生变化，方法就会执行
        this.init()
      }
    },
  methods: {

      init(){
          //判断路径是否有id值
          if(this.$route.params && this.$route.params.id){
            this.courseId=this.$route.params.id
            this.getCourseBaseInfo()
          }else{
            this.courseInfo={title: '',
                subjectParentId:'',//一级分类
                subjectId: '',//二级分类
                teacherId: '',
                lessonNum: 0,
                cover: '/static/01.png',
                price: 0}
            this.teacherList=[]
            this.oneLevelList=[]
            this.twoLevelList=[]
            this.courseId=''
            this.getTeacherAll()
            this.getOneLevel()
          }
        },

    //根据课程id查询课程基本信息
    getCourseBaseInfo(){
        course.getCourseBaseInfo(this.courseId)
            .then(response=>{
                //获取课程基本信息，通过id
                this.courseInfo=response.data.courseBaseInfoVo
                //查询所有分类，通过id
                subject.getSubjectList()
                    .then(response=>{
                        //所有获取一级分类，包括其对应的二级分类
                        this.oneLevelList=response.data.list
                        //比较获取的所有分类与回显的该课程分类
                        for (let index = 0; index < this.oneLevelList.length; index++) {
                            let oneSubject = this.oneLevelList[index];
                            if(this.courseInfo.subjectParentId==oneSubject.id){
                                this.twoLevelList = oneSubject.children
                            }
                        }
                    })
                //查询所有讲师
                this.getTeacherAll()
            })
    },

    //封面上传成功
    handleAvatarSuccess(res, file){
        this.courseInfo.cover = res.data.url
    },
    //封面上传之前
    beforeAvatarUpload(file){
        const isPNG = file.type === 'image/png'
        const isLt2M = file.size / 1024 / 1024 < 2
        if (!isPNG) {
            this.$message.error('上传头像图片只能是 PNG 格式!')
        }
        if (!isLt2M) {
            this.$message.error('上传头像图片大小不能超过 2MB!')
        }
        return isPNG && isLt2M
    },

    //当一级分类选项中的值发生改变，则触发，显示其对应的二级分类
    oneLevelChange(value){
        //value是一级分类的id值
        //遍历二级包含一级、二级分类的oneLevelList
        for (let index = 0; index < this.oneLevelList.length; index++) {
            //取得每个一级分类
            let subject=this.oneLevelList[index]
            if(value===subject.id){
                this.twoLevelList=subject.children
                this.courseInfo.subjectId = ''
            }
        }
    },
    //获取一级分类
    getOneLevel(){
        subject.getSubjectList()
        .then(response=>{
            this.oneLevelList=response.data.list
        })
    },
    
    //查询所有讲师
    getTeacherAll(){
        course.getTeacherAll()
        .then(response=>{
            this.teacherList=response.data.items
        })
    },

    saveCourse(){
        course.addCourseInfo(this.courseInfo)
        .then(response=>{
            this.$message({
                type:'success',
                message:'添加课程信息成功'
            })
            this.$router.push({ path: '/course/chapter/'+response.data.id })
        })
    },

    updateCourse(){
        course.updateCourseInfo(this.courseInfo)
        .then(response=>{
            this.$message({
                type:'success',
                message:'修改课程信息成功'
            })
            this.$router.push({ path: '/course/chapter/'+this.courseId })
        })
    },

    //保存或修改课程信息
    saveOrUpdate() {
      //通过id判断是添加还是修改操作
      if(!this.courseInfo.id){
          this.saveCourse()
      }else{
          this.updateCourse()
      }
    }
  }
}
</script>

<style scoped>
.tinymce-container {
  line-height: 29px;
}
</style>